1. Field of the Invention
This invention relates to telecommunications systems, especially telecommunication systems capable of computer telephony such as voice over internet protocol (VoIP). Specifically, the invention relates to completing an emergency, e.g. 911, call from a station/device over a data network, e.g., a private corporate local area network (LAN/IP) or the Internet, to a public network emergency facility and delivering precise location information of the caller and a call back number based on a port equipment number associated with the port from which the emergency call originated.
2. Brief Description of the Prior Art
When a caller calls an emergency number, e.g. 911 (E911), the call is routed to a Public Safety Answering Point (PSAP). In some jurisdictions, regulatory agencies require that the caller""s telephone number/callback number and/or precise physical location referred to as an Emergency Location Identification Number (ELIN), be automatically provided to the PSAP. The information in the ELIN is used to locate the caller and to call back to the caller should there be a disconnect.
A caller identification (i.e., telephone number and ELIN) may be delivered to the PSAP either in-band (e.g., using DTMF signaling) or out-of-band (e.g., using ISDN signaling) depending on the type of trunk circuit employed. Normally, for residential callers Caller ID number is sufficient for the PSAP. In some cases, the ELIN is geodetic, i.e. includes earth coordinates or geo-positional synchronous (GPS) data.
Digitally encoded voice communications that are transmitted over a network, using what is typically referred to as Voice over Internet Protocol (VoIP) may originate anywhere and possibly, follow a circuitous convoluted route to a distant destination for far-end hop-off to a public service telephone network (PSTN). Thus, placing an E911 call over a VoIP enabled telephone network, may be a problem. Heretofore, there has not been a way in an IP network (e.g., voice over IP) to identify the source location of an originating device whose destination is 911 (or other emergency number) and to route the call to the proper PSAP jurisdiction (or other designated destination).
Thus, there is a need for a way to determine the proper destination PSAP of emergency calls in an IP network and further to correctly route an emergency call from the IP network to the public network of the appropriate PSAP.
It is therefore a purpose of the invention to accurately report the emergency location of an emergency caller calling on a VoIP network to public safety personnel.
It is another purpose of the invention to accurately report the callback number of an emergency caller using VoIP to public safety personnel.
It is yet another purpose of the invention to accurately report the ELIN and callback number of a caller making an emergency call using VoIP to call a PSAP over a private network in a manner that does not interfere with features of the PBX/MLTS.
It is yet another purpose of the invention to locate an E911 caller from the source of the call, regardless of the call origination location including calls originating in an IP private network, and route the call to the most appropriate PSAP, closest to the caller.
The present invention is an IP Telephony Emergency Connections (ITEC) system and method that determines the precise origin of an emergency call and routes the call to the proper Public Service Answering Point (PSAP). A source-based routing mechanism is provided in an IP telephony type network, such as a Voice over IP (VoIP) or IP over Local Area Network/Asynchronous Transfer Mode (LAN/ATM). Emergency calls are routed to the correct PSAP jurisdiction. Emergency calls may include, but are not limited to voice calls. The routing mechanism may be deployed in any intelligent distributed or centralized network. For example, a server/switch at a gateway may include the mechanism such that the IP Telephony network can identify an E911 connection and egress to a public network at a point closest to the emergency call point of origin. Whenever a call is recognized as being an emergency number call, the call""s origin is determined during call setup establishment. Every port or end user jack in the network is assigned a Source Group Index (SGI), regardless of whether a port is physical or logical, e.g., for multi-drop. An SGI is a number or index representing each PSAP jurisdiction in the network. Port/jack level management granularity allows any server/switch to serve users that may be in different areas of multiple PSAP jurisdictions. So, all ports/jacks within the same PSAP jurisdiction are assigned the same SGI.
Advantageously, an emergency call made using VoIP is routed to the proper authorities. The routing can be provided at any network entity that is equipped with appropriate trunks, including the network entity where the call originated or, at a gateway located near the source of the call. This call handling circumvents normal call routing and may fulfill expected governmental requirements for emergency calls. Accordingly, emergency request information is sent to the correct PSAP regardless of where the user resides in an IP network.
Thus, the apparatus of the invention includes database management, emergency number detection, call routing and both ISDN and non-ISDN signaling. The present invention may be configured so that either the callback number, the ELIN, or both are transmitted to the PSAP. Further, the invention may be configured to recognize multiple emergency numbers and to give emergency calls priority over non-emergency calls.
Additional benefits and features of the invention will be apparent from the following detailed description taken together with the attached drawings.